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(No Model.) 3 SheeVts- -Sheet 1. F. M. STEVENS. Valve Geaf for Steam Engines. N0. 232,774. Patented Sept. 28,1880.

ATTESTI WA M 3 Sheets--Sheet 2.

(No Model.)

P. M. STEVENS.

Valve Gear for Steam Engines. No. 232,774. Patented Sept. 28,1880.

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3 Sheets--Sheet F. M. STEVENS. Valve Gear for Steam Engines.

Patented Sept. 28,1880.

N PETERS, PHOTOJJTHQGR .INVENTYORI APHER WASHKNGTON D C.

FRANK M. STEVENS, OF CONCORD, N. H., ASSIGNOR OF ONE-HALF OF HIS RIGHT TO JOHN H. PEARSON; SAID PEARSON ASSIGNOR OF ONE-HALF OF HIS RIGHT TO CHARLES C. PEARSON, ALL OF SAME PLACE.

VALVE-GEAR FOR STEAM-ENGINES.

SPECIFICATION forming part of Letters Patent Nol 232,774., dated September 28, 1880. Application filed March 26, 1880. (No model.)

To all whom it may concern Be it known that I, FRANK M. STEVENS, of Concord, in the county of Merrimack and State of New Hampshire, have invented certain Improvementsin SteamEngines, of which the following is a specification.

This invention relates to steamengines; and it consists, among other things, in a locomotive-engine having two inlet and two ex- IO haust valves and means to operate them, whereby the engine-pistons may continue their motion while the valves remain stationary, as when the engine is on a downgrade, without increasing the pressure in the boiler also, in a I 5 cam-barrel provided with suitable cams, combined with means to impart lateral motion to the said cam-barrel; also, in a system of sepa rate inlet and exhaust valves and cam-barrels, of eccentrics, pivoted levers, and links to con nect the eccentrics and cam-barrels with the said levers, as hereinafter set forth, and specified in the claims at the end of this specification.

The novel features of the invention lie partly in the shifting cut-off and reversing-cams, partly in the means for operating the same, partly in the means for communicating the motion from the cam to the valves, and partly in the combination of the valves with the sev- 0 eral features of the valve-gear, all as will be more fully hereinafter set forth.

In the drawings which serve to illustrate my invention, Figure 1 is a plan of the valves and gear of a locomotive in which my inven- 3 5 tion is embodied. Fig. 2 is a sectional elevation taken in the plane of the line aa; in Fig. 1. Fig. 3 is a front elevation. Figs. 5 and 6 are views of opposite sides of the cam, drawn to a scale double the size of the other figures;

and Fig. 7 shows cross-sections of the same, taken in the planes of the lines 3 y and z z in Figs. 5 and 6.

Let A A represent the engine-cylinders of a locomotive, B, the bed-plate that connects 5 them 5 C, the connecting-rods; l) D, the drivers, and E the axle on which they are fixed.

Each engine is provided with like valves and operative gear, all actuated from like points simultaneously, and consequently a detailed description of one will serve for both, like let- 5o ters being used to designate like parts.

F is a cam-shaft mounted in hearings at a, a, and provided with two cranks, b b, bent or arranged at right angles to each other. Connecting-rods c 0 take hold of these cranks and 5 5 extend back to and connect with upright levers or arms (I d, pivoted in the frame at e e, as shown. To the lower extremities of these arms are attached other connectingrods, c c, which extend back and are connected with eccentrics ff on the axle E. Cranks may sometimes be used in place of the eccentrics f f but I prefer eccentrics. These eccentrics are also set at right angles on the axle, and consequently a rotary motion of the axle will communicate a corresponding rotary motion to the shaft F. If the connecting-rods were carried directly from the eccentrics ff to the cranks Z) I) while the former are in a plane so much below the latter, the vertical play of the frame on the springs of thelocomotive would be sufiicient to dcrange the function of the parts, if not to render them entirely inoperative, as the distance between the centers of the axle E and shaft F will be constantly varying, and to a considerable degree; but with the connectingrods arranged in parallel planes at right an- I gles to the substantially vertical play of the frame on the springs this injurious effect is practically neutralized. This is another rea- 8o son for the construction shown.

On the shaft F is an elongated cam-barrel, G, which is arranged to slide longitudinally upon the shaft, it being prevented from turning by means of a spline, g. Referring to Figs. 5, 6, and 7, where this cam-barrel is more fully illustrated, 1 represents a circumferential groove between the exhaust end of the cam (that to the right) and the inlet end. This in let end consists of two spirally-constructed cut- 0 off cams, 2 and 3, the former of which may be designated the go-ahead inlet-cam, and the latter the backinginlet-cam. These cams are alike, but are arranged in inverse order. As a spirally-arranged cut-off cam is not of it- 5 self new, it will not be necessary to describe its construction more fully. The exhaust end consists of two exhaust-cams, 4c and 5, the for mer of which may be designated the goahead exhaust-cam, and the latter the backing exhaust-cam. The elongated cam-barrel Gr may be considered as a cylinder, having a diameter equal to the section taken on the line y y in Figs. 5 and 6, and as shown at the left in Fig. 7, and the cams 23 4 5 may be considered as enlargements on said cylinders. The exhaustcams 4 5 each extend half-way around the cylinder,- and there is a zone between them where the enlargement extends all around the cylinder in the form of abelt, 6. Through this belt the section shown to the right in Fig. 7 is taken. Thus at 6 I have an enlarged cylinder between the exhaust-cams, and a lesser zone consisting of the cam-barrel itself at 7 between the inlet-cams. The object of these will be explained farther on.

On the end of the barrel G is formed a clutchgroove, h, with which engages a fork, i. This fork has a nut or threaded bore on its lower end, which engages a horizontally-arrangod screw, j, that has fixed hearings on the main frame. This screw bears a miter or bevel wheel, 70, that engages a bevel-wheel, b, on a shaft arranged at an angle to the screw j. At the other end of this latter shaft is another bevel-wheel, t, which meshes with a larger wheel, m, on a vertical shaft, provided with a suitable hand-wheel, H, so that by rotating this hand-wheel the screw j may be rotated, the fork t caused to travel thereon, and the cam-barrel G be caused to move longitudinally on its shaft.

I I are the inlet-valves, and J J the exhaustvalves. These are preferably oscillating valves, which may be of any suitable character, or single-acting slide-valves may be used instead. The valves shown are similar to that illustrated in my patent of July 16, 1878, and numbered 205,982. To the stems of these valves are fixed arms a n, and these arms are arranged to connect with levers 0 0, (see Fig. 4,) pivoted or hinged at their bottom ends, as shown. Each valve has its arm n and lever 0, and the valves are coupled together in pairs, the exhaust together and the inlet together, by means of springs 19 p, arranged between the pairs of levers o o and adapted to keep them pressed inward or toward each other. The arms a n are connected to the levers o 0 by a ball-andsocket connection, consisting of oblong hemispherical-ended blocks q q, through which the tie-bolts r r pass, as shown. These tie-bolts may, if desired, be utilized from the prolonged ends of the spring 19. The nuts on the outer ends of the bolts 1 1 have also hemispherical faces, and these, as well as the convex ends of the blocks q, engage corresponding concaves in the levers and arms.

The cam-barrel G,with its cams, is arranged to rotate between the levers 0 0 in such a manner that the springs 19 19 will cause the levers to clasp it, and they are provided with rounded protuberanees s s to bear on the barrel and cams. The go-ahead cams 2 and 4, the zones or belts 6 and 7, and the backing-cams 3 and 5 are the same distance apart, and are spaced to correspond with the distance apart of the valve-levers 0 0, so that when the levers of the exhaust-valves engage, say, the cam 4 those of the inlet-valves will engage the cam 2.

The operation is as follows: Suppose the locomotive to be going ahead. The driveraxle E communicates rotary motion to the shaft F, and through it to the cam-barrel G and its various cams. Each revolution. of the axle imparts a corresponding revolution to the cams. The cam 2 in its revolutions acts alternately upon the levers 0 0, pressing them outward, and they in turn act upon the arms an, to oscillate the valves and admit the steam to the cylinders. At the same time the cam 4 acts in a like manner upon the exhaust-valve levers to permit the escape of the steam.

If the engineer wishes to reverse the engine he shifts the valve mechanism through the medium of the hand-wheel H. The rotation of the said wheel in the proper direction causes the cam-barrel G to move along its shaft in a manner hereinbefore described until the backing-cams 3 and 5 take the places before occupied by the cams 2 and 4. It will be observed, however, that in making this change the belt or zones 6 and 7 must coincide while the movement is being made with the levers connected, respectively with the exhaust and inlet valves, and the result will be that the two inlet-valves will be closed and the two exhaust-valves thrown wide open, and all simultaneously. This clears both ends of the cylinders of steam before the change is .or can be made from backing to going ahead, or vice versa. While the cams are in this position the valves are stopped from moving, although the engine-pistons may yet be in motion, and in going down a grade while the cams are so set the pistons operate freely, and can neither compress steam nor air in the cylinder or form a vacuum. This is one of the most important features of my valve-gear-that I am enabled to throw open both exhaust-valves and close both inlet-valves simultaneously. Ordinarily with this gear the throttle-valves will not be employed, as the setting of the valves, as just described, effectually cuts off all the steam from the cylinders.

To enable the cams to be brought successively under the protuberances on the levers by a lateral movement as well as a rotary movement, I provide inclines or easements, as shown, avoiding all abrupt offsets.

The springs serve to close the valves at the proper moment, and each lever 0 may have a separate spring. In some cases I may employ a positive force, as a can], in lieu of a spring, to close the valves.

The groove 1 is of no importance, and it maybe omitted. It simply serves to mark.

the center of the cam-barrel.

As shown, the cams employed on one cylinder are arranged oppositely to those on the other, and the two sets of cams move outwardly and inwardly at the same time when shifted.

They might, however, be differently arranged, so as to move in the same direction simultaneously. I prefer to employ two distinct screws, 3', one for each cylinder, as shown, provide each with a bevel-wheel, k, and drive them from a common bevel-wheel; but one screw for both would answer very well. I do not care to confine myself to any particular arrangements of these gear-wheels for operating the screw or screws j, nor to the use of screws for effecting the longitudinal movement of the cam-barrel, as a rack and pinion or other movement might be employed for this purpose.

The ball-andsocket connection of the arms 0 0 with the valve-levers gives perfect freedom to the movement without detracting from its positiveness; and the employment of the levers enables me to'get a greater movement of the valve with a given throw of the cams than could be had by causing the latter to act directly upon the levers a n. In some cases the levers might be dispensed with, and the arms a n be arranged to bear directly upon the cams or barrel G.

I could rotate the shaft F from two cranks formed on the driver-axle in lieu of the eccentricsff; but these are costly, and cannot be adjusted with ease like an eccentric. It is not absolutely necessary that the eccentrics and cranks shall be at right angles to each other, but this arrangement is preferable.

As a matter of convenience I contemplate so constructing the gearing that less than one revolution of the hand-wheel II will be sufficient to shift the cams, and to so mark the wheel that the engineer may know at a glance in whatposition the valves stand.

I do not broadly claim a lever and two links to connect two rotating shafts, as I am aware that such a contrivance has been used with the lever pivoted near one end, the connecting-rods being extended from the said lever both in the same direction.

Having thus described my invention, I claim- 1. In a locomotive-engine, two inlet and two exhaust valves, and means, substantially as described, to operate them, whereby the engine-pistons may continue their motion while the said valves remain stationary, for the purposes set forth.

2. In a locomotive-engine, cam-barrels provided each with two sets of cams to operate two inlet and exhaust valves, combined with a hand-wheel and screw-shafts and means to connect the said screw-shafts with the said cam-barrels, substantially as described.

3. In a locomotive-engine, the cam-barrels and their cams to operate the separate inlet and exhaust valves, as described, combined with the eccentrics, pivoted levers, cranks, and shaft, and the connecting-links to join the said levers with the said eccentrics and cranks, substantially as described.

4. The shaft F, combined with the movable cam barrel provided with cams 2 3 e 5 and belts or zones 6 and 7, substantially as and for the purposes set forth.

5. In a locomotive, the driver-axle, its eccentrics, the centrally-pivoted upright levers, and the connecting-rods c c, joined with the lower ends of the said levers and with the eccentrics, combined with the rotating cam-shaft F and the connecting-rods c 0, joining it with the upper ends of the said levers d, the two sets of connecting rods 0 and 0 being extended in opposite directions from the upright levers with which they are joined, substantially as and for the purposes set forth.

6. The cam-barrel G, provided with inlet and exhaust moving cams arranged between the valves, as shown, combined with the said valves and their arms an, arranged to operate all substantially as set forth.

7. In combination, the shaft F, a cam-barrel thereon provided with cams 2, 3, 4t, and 5 and zones or belts G and 7, means to shift the cambarrel on the said shaft, the levers 0 0, the

arms a n, the valve-stems, and the valves I I and J J, to operate substantially as set forth.

8. In combination, the rotary shaft F, the cam-barrel provided with the inlet and exhaust cams 2 3 4 5, and the clutch-groove h, the fork, and the screw, to operate substantially as set forth.

9. In combination, the \vheelHand its shaft, the gear-wheel m, Z Z, and k, the screw j, fork "i, and the cam-barrel arranged to slide thereon, substantially as and for the purposes set forth.

10. In combination, the driver-axle, its eccentrics, the pivoted levers, the connectingrods 0 c and c c, the shaft F, provided with cranks, the cam-barrels provided with cams for operating the valves, the levers 0 o, the arms a n on the valve-stems, and the valves I I and J J, substantially as and for the purpose set forth.

11. The cam-barrel and its cams 2 3 4 5, combined with the pivoted levers 0, bearing upon opposite sides of the cam-barrel, and spring 19, to keep such levers pressed up to the said cams and barrels, and the arms a and their connected valves, substantially as set forth.

12. In combination, the levers 0 0, spring 19, tie-rods r 1", blocks q q, and the arms a n on the stems of the valves, to operate substantially as and for the purpose set forth.

13. In an engine, two independent inlet and two independent exhaust valves, combined with mechanism, substantially as described, to simultaneously close the two inlet-valves and throw open the two exhaust-valves when it is desired to stop or reverse the engine, substantially as and for the purpose specified.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

FRANK M. STEVENS.

Witnesses:

HENRY OONNETT, ARTHUR G. FRAsER. 

